Paper Number
IN10
Session
Flow Induced Instabilities and Non-Newtonian Fluids
Title
Fully developed capillary flow of a shear-banding solution of wormlike micelles requires L/d > 100
Presentation Date and Time
October 21, 2019 (Monday) 3:45
Track / Room
Track 4 / Room 305B
Authors
- Salipante, Paul F. (NIST, Polymers & Complex Fluids)
- Dharmaraj, Vishnu (NIST)
- Hudson, Steven (NIST)
Author and Affiliation Lines
Paul F. Salipante, Vishnu Dharmaraj, and Steven Hudson
NIST, Gaithersburg, MD 20899
Speaker / Presenter
Salipante, Paul F.
Text of Abstract
The viscosity of a shear-banding wormlike micelle solution at high shear rates is investigated using capillary rheology and particle streak velocimetry. Measurements of the flow profile and pressure gradient show an extended entrance region, which exceeds a length to diameter ratio of 100, to reach a fully developed flow. We characterized this entrance region for capillaries with different cross-sections and use the results to select a downstream portion of the capillary where capillary rheology measurements can be made on fully developed flow. We observe a shear- thinning power- law behavior for all channel geometries above the plateau stress until reaching the solvent viscosity limit.